[译]Java 设计模式之组合

(文章翻译自Java Design Pattern: Composite)

组合模式相对来说是比较简单的，但是它在很多设计中被用到，比如SWT、Eclipse工作空间等等。它创建了一个可以通过唯一的方法访问的继承树。

类图

下面的代码实现了下面树的结构

Java 代码

import java.util.List;
import java.util.ArrayList;

//Component
interface Component {
    public void show();
}

//Composite
class Composite implements Component {

    private List<Component> childComponents = new ArrayList<Component>();

    public void add(Component component) {
    	childComponents.add(component);
    }

    public void remove(Component component) {
    	childComponents.remove(component);
    }

	@Override
	public void show() {
		for (Component component : childComponents) {
        	component.show();
        }
	}
}

//leaf
class Leaf implements Component {
	String name;
	public Leaf(String s){
		name = s;
	}
    public void show() {
        System.out.println(name);
    }
}

public class CompositeTest {

    public static void main(String[] args) {
        Leaf leaf1 = new Leaf("1");
        Leaf leaf2 = new Leaf("2");
        Leaf leaf3 = new Leaf("3");
        Leaf leaf4 = new Leaf("4");
        Leaf leaf5 = new Leaf("5");

        Composite composite1 = new Composite();
        composite1.add(leaf1);
        composite1.add(leaf2);

        Composite composite2 = new Composite();
        composite2.add(leaf3);
        composite2.add(leaf4);
        composite2.add(leaf5);

        composite1.add(composite2);
        composite1.show();
    }
}